In many areas of the country, air conditioning needs are significant, especially during summer months. In some states, such as Florida and Texas, and others in the south, those needs are significant throughout most of the year. Not only do high outdoor temperatures affect indoor temperatures whenever large windows are used, but there is typically a substantially increased need for cooling to offset the greenhouse effect that can cause heat to be trapped inside. In areas where the climate is warm, the demand for air conditioning can cause a significant portion of the energy costs to be devoted to air conditioning needs, i.e., air conditioning can become a significant factor and/or percentage of the entire energy costs, and therefore, the cost of keeping a home or business cool can become a heavy burden.
Another problem associated with keeping buildings cool is that the energy demand often peaks during the daytime hours, which, in turn, increases the energy rates during those hours. That is, air conditioning needs are typically highest during the day, which is when the sun is shining, and the outdoor temperatures are at their highest, but which is also when most businesses are operating, such that, they tend to drive up the energy rates during those periods, which is when the energy is needed most. Many utility companies charge more during the peak daytime periods, to offset the higher demand and therefore cost of supplying energy during those periods. This is especially true during the warmest summer months. During the winter months, when heating needs are greater than cooling needs, the correlation between the two isn't quite as acute. During the winter months, it is usually warmer during the day than during the night, and therefore, the overall energy needs during the day are not quite as high, as they are during the summer. Nevertheless, to the extent the cost of energy is higher during the highest demand periods, the cost of maintaining comfortable temperatures in the home or business can be tremendously high.
Due to these problems, attempts have been made in the past to develop and implement cost-saving systems that use alternative energy sources to reduce the overall cost of energy during the high demand periods. For example, solar energy systems have been developed and used to provide extra heating for homes and businesses. Nevertheless, energy derived from the sun, by its very nature, cannot normally be efficiently used for cooling purposes. Although solar energy can be converted into electricity, and then, the electricity can be used to power an air conditioning system, the cost of converting the solar energy to produce electricity to do so can be prohibitively high.
Past systems have also incorporated other natural alternative energy sources, such as the wind, to generate electricity, which can then be used for both heating and cooling. The difficulty of using wind, however, is that the wind may not always blow when the demand exists. For example, the wind can be unpredictable, and uncertain, wherein the wind may not blow with sufficient force and regularity during the times when energy is needed most. In fact, in many cases, the wind may blow harder and more consistently at night, whereas, the need for energy, as discussed above, may be greatest during the day.
To resolve these issues, attempts have been made in the past to store the energy generated by wind, so that it can be used later, when it is needed most. Past attempts include the use of small wind turbine generators in the order of 10 to 50 kW power which use batteries to store energy during excess wind power periods to compensate for when wind power is deficient. There are also projects designed to store wind energy in underground caverns, in the form of compressed air energy, which use supplementary combustion to improve electrical power output. Despite some advantages of these past systems, which attempt to store wind-generated energy, they also have certain shortcomings, making them difficult or inefficient to use.
One type of air conditioning system that is in current use and has been relatively successful in lowering energy costs is a thermal energy storage system (TES). In this system, water is typically chilled during times when electricity rates are relatively low, and then, the chilled water is stored in large storage tanks so that the chilled water can be used later to provide cooling for an air conditioning system, i.e., when electricity rates are relatively high. The system chills the water when energy rates are relatively low, such as at night, and then stores it in a water temperature stratified tank, so that later, when it is most needed, i.e., during peak daytime hours, it can be used to provide cooling for the associated facility. This enables the facility to consume electrical energy from the utility power grid during relatively low-cost energy periods, i.e., at night, and then use the energy to cool the facility during relatively high-cost energy periods, i.e., the day, wherein overall energy costs can be reduced.
One of the drawbacks of these systems, however, is that the energy must be purchased directly from the utility companies, notwithstanding that it can be purchased at a lower rate during off-peak hours. For these reasons, an improved method and system is needed that can be used to provide cooling for an air conditioning system, which can not only be operated during peak daytime hours, but which is able to further reduce the end user cost and overall usage of energy.